Field of the Invention
This invention relates generally to an apparatus for lifting, lowering, and self-propelled transit of a person having limited use of their legs or limited leg strength.
Description of Related Art
Many people require assistance moving between standing and seated positions. To reduce dependence on others, numerous devices have been developed, particularly in regard to performing everyday activities.
A conventional device for the transit of partially incapacitated persons includes U.S. Pat. No. 5,785,070 to Block et al., which provides an apparatus having a first set of handles used to assist the person when in a standing position and a second set of handles provided in a position beneath the first set of handles. The second set of handles provides resistance for use when rising to a standing position. However, the apparatus of Block et al. requires use of a person's own strength to achieve the standing position, and creates an awkward sitting scenario wherein the user has to lean backward, shift weight onto the second set of handles, which may be behind and beneath the user, and then bend their knees to complete the sitting motion.
Another conventional device is described in U.S. Pat. No. 6,503,176 to Kuntz, which provides a device having a compressed air assembly and a support sling to lift the user from a seated position. The device of Kuntz does not require use of upper body strength to achieve a standing position. However, the device requires use of a compressed air cylinder for power, which is inconvenient to a user due to the weight, cost and impracticality of having to transport and refill compressed air tanks. An additional limitation of Kuntz and other conventional devices is that a user is lifted along a path that differs from a natural standing motion. The unnatural lift motion makes conventional device uncomfortable to use and reduces stability.
Yet another conventional device is described in U.S. Pat. No. 6,733,018 to Razon, which provides a stand up walker for supporting the body weight in a standing position. In Razon, a pair of upper lift arms is mounted on a walker frame with a lift spring, which lifts a user. However, the lifting motion provided by the device of Razon is unnatural, inefficient, and generally painful when the point of application of lifting force is provided at the armpits. While being lifted from the hips using a sling, ensuring the stability of the device is a major challenge since the center of gravity of the person being lifted is usually outside the footprint of the device. Also, for gas springs to effectively operate, exertion of a user's own strength is required during the lifting phase, to ensure that the gas springs compress during the sitting phase. In addition, gas springs generally do not provide a smooth lifting motion.
Conventional devices fail to provide a user with a stable lifting apparatus that can be repeatedly used without fatigue. Conventional devices also fail to lift a user along a natural path of the lifting motion.
To overcome shortcomings of conventional devices, the present invention provides an apparatus and method for lifting a person along a natural path of motion, from either a hip or shoulder lifting point, both of which provides a natural lifting operation. The apparatus can support the user's weight at the buttocks or alternatively at the armpit/shoulder region while maintaining stability throughout the entire range of motion. The user of the apparatus of the present invention can also utilize a sling thereof as a seat when not in use as a walker. The present invention also provides lifting/lowering assistance between seated/standing positions, functions as a standard walker and/or gait trainer, and also provides a method for lifting assistance to provide exercise during patient rehabilitation.